August 5th 2011 NASA's Juno spacecraft blasted off on a 5-year voyage to a freakish world: planet Jupiter.
Jupiter has a long list of oddities. For one thing, it's enormous,
containing 70% of our solar system's planetary material, yet it is not
like the rocky world beneath our feet. Jupiter is so gassy, it seems
more like a star. Jupiter’s atmosphere brews hurricanes twice as wide as
Earth itself, monsters that generate 400 mph winds and lightning 100
times brighter than terrestrial bolts. The giant planet also emits a
brand of radiation lethal to unprotected humans.
Jupiter's strangest feature, however, may be a 25,000 mile deep
soup of exotic fluid sloshing around its interior. It's called liquid
metallic hydrogen.
"Here on Earth, hydrogen is a colorless, transparent gas," says
Juno principal investigator Scott Bolton. "But in the core of Jupiter,
hydrogen transforms into something bizarre."

This cut-away illustrates a hypothesized model of the interior of Jupiter

Jupiter is 90% hydrogen, with 10% helium and a
sprinkle of all the other elements. In the gas giant’s outer layers,
hydrogen is a gas just like on Earth. As you go deeper, intense
atmospheric pressure gradually turns the gas into a dense fluid.
Eventually the pressure becomes so great that it squeezes the electrons
out of the hydrogen atoms and the fluid starts to conduct like a metal.
What’s this fluid like?
"Liquid metallic hydrogen has low viscosity, like water, and it's a
good electrical and thermal conductor," says Caltech's David Stevenson,
an expert in planet formation, evolution, and structure. "Like a
mirror, it reflects light, so if you were immersed in it [here's hoping
you never are], you wouldn't be able to see anything."

Jupiter's hydrogen sea

Here on Earth, liquid metallic hydrogen has been made in shock
wave experiments, but since it doesn't stay in that form it has only
been made in tiny quantities for very short periods of time. If
researchers are right, Jupiter's core may be filled with oceans of the
stuff.
There's so much LMH inside Jupiter that it transforms the planet
into an enormous generator. "A deep layer of liquid metallic hydrogen
and Jupiter's rapid rotation (about 10 hours) create a magnetic field
450 million miles long -- the biggest entity in the solar system," says
Bolton. Jupiter's magnetosphere can produce up to 10 million amps of
electric current, with auroras that light up Jupiter’s poles more
brightly than any other planet.
Although scientists are fairly sure that liquid metallic hydrogen
exists inside Jupiter, they don't know exactly how the big planet's
interior is structured. For instance, where does the hydrogen turn into a
conductor? Does Jupiter have a core of heavy elements inside? Juno's mission is to answer those key questions. "By mapping Jupiter's magnetic field, gravity field, and
atmospheric composition, Juno will tell us a great deal about the
make-up of Jupiter's interior."
It's important to understand this behemoth because it wielded a
lot of influence in the solar system's formation. After the sun took
shape out of the solar nebula, Jupiter formed from the majority of
leftover material. The state and composition of the material remaining
just after the sun formed are preserved in Jupiter.
"It holds the heirloom recipe that made our solar system's first planets," says Bolton. "And we want it."
With last Friday's launch, "Jupiter becomes our lab, Juno our
instrument, to unlock the secrets of gas giants," he says. And what Juno
discovers could be very freakish, indeed.Credit: NASA

Tuesday, October 6, 2015

There's an urban legend about a woman killed by a shaft of frozen
urine fallen from a plane's leaking toilet. Then there's the one about
pennies dropped from the top of the Empire State Building, passing
through pedestrians' skulls like bullets. Then there's the one about
telephone pole-sized tungsten rods dropping from an orbital weapons
platform at 36,000 feet per second to impact the earth below with the
force of a meteor strike.

Guess which one you won't find on Snopes under "stupid bullshit?"
Yes, enormous Swords of Damocles hanging in space are one more reason
to lie awake at night, thinking about how much safer we feel thanks to
science.